A storage area network (SAN) may be implemented as a high-speed, special purpose network that interconnects different kinds of data storage devices with associated data servers on behalf of a large network of users. Typically, a storage area network includes high performance switches as part of the overall network of computing resources for an enterprise. The storage area network is usually clustered in close geographical proximity to other computing resources, such as mainframe computers, but may also extend to remote locations for backup and archival storage using wide area network carrier technologies. Fibre Channel networking is typically used in SANs although other communications technologies may also be employed, including Ethernet and IP-based storage networking standards (e.g., iSCSI, FCIP (Fibre Channel over IP), etc.).
As used herein, the term “Fibre Channel” refers to the Fibre Channel (FC) family of standards (developed by the American National Standards Institute (ANSI)) and other related and draft standards. In general, Fibre Channel defines a transmission medium based on a high speed communications interface for the transfer of large amounts of data via connections between varieties of hardware devices.
In a typical SAN, one or more FC switches are used to communicatively connect one or more server devices with one or more data storage devices. Such switches generally support a high performance switching fabric and provide a number of communication ports for connecting to other switches, servers, storage devices, or other SAN devices. Other high performance fabrics may employ different fabric technologies, such as Infiniband.
Other networking technologies, such as Ethernet, may also be employed in communicating between computing and networking devices. An evolving standard referred to as Fibre Channel over Ethernet (FCoE), for example, is modeled as a Layer3 protocol on top of a Convergence Enhanced Ethernet (CEE) fabric. A typical topology includes FCoE switches connected at a boundary between a Fibre Channel fabric and a CEE fabric. When deployed in such a multi-protocol fabric, an FCoE F_PORT is the primary interface for all storage traffic between an FCoE N_PORT (e.g., of an FCoE host) and an FC resident storage target. As such, failure (or disabling) of the FCoE F_PORT can significantly disrupt I/O between FCoE hosts in the CEE fabric and FC targets that are interconnected in the FC fabric. For example, in a typical configuration, an N_PORT of an FCoE host is required to initiate Link Keep Alive Extended Link Services (LKA ELS) between the FCoE N_PORT and the FCoE F_PORTs in the Fibre Channel fabric. When an FCoE F_PORT failure is detected, the FCoE N_PORT is required to initiate a new FLOGI, followed by a PLOGI to each FC target, to revive communications. Such disruptions in communications are undesirable, and the existing approach is not well scalable.